It just depends on what church you are talking about specifically, as churches in both communions can have drastically different lengths. Also, there is no uniform liturgical heritage in the Non-Chalcedonian communion, so a Coptic round of services might be longer than an Armenian one.

My Orthodox parish offers Great Vespers and confession on Saturday evenings which lasts for about 45-50 minutes, and then a full Matins and Divine Liturgy every Sunday. On Sunday mornings, Matins starts at 8:00AM and the Divine Liturgy gets over between 11:30AM-12:00 noon depending on the Sunday. Sometimes it goes even longer if there are extra services tacked on like on Pentecost with kneeling Vespers, which adds another 45 minutes.

So just on a typical Sunday morning services last 3 1/2 to 4 hours.

I visited a local Coptic church once and I think I remember it lasting over 3 hours. I can't vouch for times in the Armenian, Ethiopian or Syriac churches, but also keep in mind that there times probably vary from church to church as well depending on how fully they perform the services.

The Liturgy at my church lasts for 2 hours, extended by baptisms, easter processions etc. That is the usual time for a coptic liturgy, other oriental liturgies are similar. Week day liturgies are shorter, but only a little. When I attended the unction of the sick and divine liturgy it all lasted 2 ans 1/2 hours. Most liturgies are 2 hours so for an average sunday prepare for that.

In the Coptic Church, the prayers of the liturgy itself takes about 2-2.5 hours depending on how fast the priest prays or which version (long or short) of hymns are sung. The rest depends on how large the congregation is for the distribution of the Holy Mysteries. My church is ginormous so it takes about 30-45 minutes for distribution since we only have 4 priests for a large congregation. Other churches take 15 minutes.

Also, on feast days, liturgies are longer since a different liturgy is prayed and there are more hymns (Liturgy of Saint Basil is prayed on normal days and Liturgy of Saint Gregory is prayed on Feasts).

Usually on Sundays, most Armenian parishes in West begin with the Jamerkutyun (night/morning services) which lasts about 1 hour and then the Divine Liturgy starts which lasts 2-2 1/3 hours, depending on various factors. So on any given Sunday, you could be there for 3 hours.

The liturgy in the Eastern Orthodox Church can last from 1.5 to 2.5 hours, depending on whether the liturgy of St. John or St. Basil is used. It also depends on whether the priest chooses to include or omit parts, such as the Litany of the Catechumens. Hierarchical Liturgies can last up to 3 hours!

The liturgy in the Eastern Orthodox Church can last from 1.5 to 2.5 hours, depending on whether the liturgy of St. John or St. Basil is used. It also depends on whether the priest chooses to include or omit parts, such as the Litany of the Catechumens. Hierarchical Liturgies can last up to 3 hours!

And on the style of chant used. Byzantine melodies tend to be far longer than their Russian counterparts.

Usually on Sundays, most Armenian parishes in West begin with the Jamerkutyun (night/morning services) which lasts about 1 hour and then the Divine Liturgy starts which lasts 2-2 1/3 hours, depending on various factors. So on any given Sunday, you could be there for 3 hours.

There is no Armenian equivalent of vespers or All- Night Vigil on the day before?